For vehicles, electronic transmission-shift controls and drivetrain controls may be used for the control of the internal combustion engine, of couplings and converters of the drivetrain and of the internal combustion engine. In conjunction with a selector lever guided in a gearshift lever gutter disposed in a center console, these systems permit selection of the driving mode by the driver. In this context, the positions P for parking, R for reverse gear, N for neutral-idling position and D for the permanent position for forward gear, as well as, for example, the gear positions 4, 3, 2 and 1 for a five-speed transmission are available to the driver for the position of the selector lever. However, some designs of transmission-shift controls, thus the Tip-/Steptronic, also permit direct selection of a gear.
In such systems, if the driver leaves the accelerator unactuated when the vehicle is in motion, then overrun sets in, so that the drive applies at the wheels a torque counteracting the vehicle movement. For instance, the drag torque resulting therefrom is desired when the vehicle should be braked during downhill driving. However, it is disadvantageous that the drag torque leads to increased fuel consumption, since the energy received from the drivetrain in overrun is dissipated.
It is possible to avoid these losses by a coasting operation which is achieved, for example, by disengaging an automatic clutch. According to one design, with the accelerator unactuated, the clutch is disengaged in response to the selection of an ECO shift program using a switch in the cockpit. However, this design approach again has the disadvantage that the use of the coasting operation cannot be controlled by the driver according to the requirements, since this operating mode can only be selected by the driver in connection with a particularly economical shift program.